The race for the Republican presidential nomination continues to take surprising turns. Yesterday, insurgent candidate Herman Cain suspended his campaign, saying he could no longer deal with the distractions caused by allegations of sexual harassment and an extramarital affair.

As Cain's star has diminished, former House speaker Newt Gingrich has emerged as the leading alternative to one-time presumptive front-runner, Mitt Romney. Last night, Gingrich defended his claim on conservative votes on a Fox News candidate forum, moderated by Mike Huckabee.

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CORNISH: ...by him earlier this year.

: Well, that's a really good question. Newt Gingrich does have a history of grandiosity and of suicidal implosions just as he reaches a pinnacle of power. His speakership was certainly an example of fact. On the other question about Gingrich is does he have the organization to go for the long haul?

Mitt Romney is ready in all 50 states. He's ready to go the distance. Newt Gingrich is doing this more or less on the fly. And don't forget, this year the Republican primaries are set up so that the award delegates proportionately in many states. That means that the candidate who comes in second still gets delegates. And that means you have to have the money and the organization to go all the way through all the primaries. And we do know if Gingrich can set that up at this late date.

CORNISH: How vulnerable is Mitt Romney at this point? It seems like he's vulnerable to challenge. Is there something about him or his campaign that's just failing to connect?

: Well, one of the strange things about this primary campaign is how long Romney went without getting a concerted attack or a challenge from many of the other candidates. He really got a pass. No one went after him very effectively in the debates. Then, last week, he sat down with Brett Baier for an interview on Fox News, and he seemed testy and less assured

I think that Romney has had some trouble connecting with voters. There is still suspicion of him among conservative Republicans. But the question for Romney has always been, does he have a glass jaw? And we don't know the answer to that yet.

CORNISH: Mara, yesterday we saw Herman Cain give a speech suspending his campaign. And it looks like the end of him for this election season. We're going to have more on that. But his supporters say he was done in by accusers with no proof, and the news media too willing to believe the worst.

Mara, is he the victim here?

: Certainly his supporters believe he's the victim, but that is not what did him in. It wasn't the accusations. It was more how he and his campaign handled them. That is the criticism you hear over and over again from Republicans, saying if he can't handle these kinds of accusations - this is part of the rough-and-tumble of politics today- then how can he handle a campaign against President Obama?

CORNISH: NPR national political correspondent Mara Liasson, Mara, thanks so much for speaking with us this morning.